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Biomedical subjects

W F Long

Publications and source records attributed to W F Long.

At least 37 records · Page 2Linked to original sources
PubMed1992

Patterns of angiogenic response to mast cell granule constituents.

Agents derived from mast cell granule constituents, and compound 48/80 which stimulates release of mast cell granules, have been used by us to develop new methods for quantitating angiogenesis in the chick chorioallantoic membrane. Two of these methods provide different insights, demonstrating different patterns of response to dosage and over time, produced by different agents. Counting mesenchymal blood vessels is convenient for obtaining dose-response data. Histamine and compound 48/80 have been shown previously to give a sigmoid dose-response curve resulting in a plateau before the lethal dose. This contrasts with the effect of porcine sodium heparin (Evans Biologicals) which results in a minor increase then a relative decline in vessel number due to a failure of growth. Here, the ability to produce angiogenesis or antiangiogenesis appears to be dose-dependent. Measurement of the changes in DNA synthesis, leading to visible angiogenesis, may be performed once the optimal angiogenic dose is known, and again distinctive patterns of response with different agents have been found. Histamine results in a fall then rise to a peak at 36 hr. We now show that two types of heparin each produce a peak at 12 hr. Compound 48/80 results in a distinctive pattern that looks like a composite of the histamine and especially the heparin effects, and this suggests that both are relevant to induction of angiogenesis by mast cells. The elicitation of this pattern of response also provides a method, additional to electron microscopy, for discovering whether or not an angiogenic substance is likely to operate via mast cell stimulation. Such characteristic patterns offer a new way of classifying angiogenic substances.

Animals↗
PubMed1991

Heparinase II from Flavobacterium heparinum. HPLC analysis of the saccharides generated from chemically modified heparins.

Saccharides produced by the action of heparinase II on native pig mucosal heparin (heparin IS), de-N-sulphated heparin (heparin IH), N-acetylheparin (heparin IA), de-N/O-sulphated heparin (heparin IVH), de-O-sulphated heparin (heparin IVS) and de-O-sulphated N-acetylheparin (heparin IVA) were analysed by reversed-phase HPLC using Spherisorb ODS2. Fractions obtained by gel filtration with Bio-Gel P-4 were similarly examined. Heparin IS gave delta UA-2S----GlcNS-6S (IS) as the major unsaturated disaccharide and lesser amounts of delta UA----GlcNS-6S (IIS), delta UA-2S----GlcNS (IIIS), delta UA----GlcNS (IVS), delta UA-2S----GlcNAc-6S (IA), delta UA----GlcNAc-6S (IIA), delta UA-2S----GlcNAc (IIIA) and delta UA----GlcNAc (IVA). Heparins IA, IVA and IVS gave as the predominant unsaturated disaccharide that corresponding to the major repeat structure of the polymer. These were respectively delta UA-2S----GlcNAc-6S (IA), delta UA-GlcNAc (IVA) and delta UA----GlcNS (IVS). Minor disaccharides from the heterogeneous structure in native pig heparin and from residual O-sulphates after the de-O-sulphating process were detected. Heparin IH was degraded more slowly than any of the N-substituted heparins. The predominant unsaturated disaccharide was IH, which was derived from the major repeating unit. In addition, disaccharides IIH, IIIH, IA, IIA and IVA were detected. Heparin IVH showed little degradation, the unsaturated disaccharide IVH not being detected after 24 h. Disaccharide IVA was obtained from the heterogeneous sequence in heparin IVH. Several higher oligosaccharides were identified in the gel-filtration fractions including saccharides from the linkage region (for heparin IS and IVA) and the anti-thrombin binding site (for heparin IS only). A tetrasaccharide and hexasaccharide, with the structures delta UA----GlcNAc----UA----GlcNAc and delta UA----GlcNAc----UA----GlcNAc----UA----GlcNAc, were present in the HPLC profiles of heparins IA and IVA.

Animals↗
PubMed1991

Heparin-polypeptide interaction. Near-i.r. spectroscopy in an anhydrous dispersant allows the involvement of polymer-associated water to be assessed.

Involvement of polymer-associated water in the interaction of heparin with poly-L-arginine and poly-L-lysine was studied by i.r. spectroscopy of complexes suspended in a non-aqueous dispersant. Movement of i.r. absorption bands due to heparin-associated water to lower frequencies upon polymer interaction indicates that hydrogen-bonding accompanies complexation. We suggest that this bonding includes water bridging between the interacting species, and that the resulting changes in water chemistry may affect the biological activity of such interacting macromolecules.

Heparin↗
PubMed1991

Heparinase II from Flavobacterium heparinum. Action on chemically modified heparins.

Five chemically modified heparins were derived from native pig mucosal heparin (pig heparin Is). These were de-N-sulphated heparin (heparin IH), N-acetylheparin (heparin IA), de-N/O-sulphated heparin (heparin IVH), de-O-sulphated heparin (heparin IVs) and de-O-sulphated N-acetyl-heparin (heparin IVA). Their structures were studied by 13C-NMR spectroscopy at 90.56 MHz. Native heparin and the derivatives were incubated with Flavobacterium heparinase II at 25 degrees C. The progress of degradation was followed by the delta A235 and the final composition examined by gel filtration with Bio-Gel P-4. Native heparin (Is) was readily degraded by heparinase II and, with the exception of heparin IVH for which degradation was negligible, the chemically modified derivatives were also degraded. Approximately 90% of the saccharides from heparins Is, IA, IVs and IVA were disaccharides and tetrasaccharides. For heparin IH, which was degraded more slowly, the proportion was 65%. Heparins Is, IVs and IVA underwent initial rapid degradation. The digestion of heparin Ia proceeded rapidly after an initial lag phase. The undegraded polymers produced similar elution profiles from Bio-Gel P-4. Following the action of heparinase II on heparins Is, IA, IVs and IVA, the elution profiles revealed a major peak of disaccharides and minor peaks of higher oligomers. The profile of heparin IH revealed a greater proportion of intermediate-molecular-mass saccharides. Our results demonstrate a broad specificity for heparinase II. It is capable of lysing both N-acetylated and N-sulphated heparins independent of O-sulphation. Heparinase II will also degrade heparin derivatives that are non-N-substituted provided that they are O-sulphated.

Animals↗
PubMed1991

Infrared spectroscopy of heparins suggests that the region 750-950 cm-1 is sensitive to changes in iduronate residue ring conformation.

By careful definition of polymer environment, heparin i.r. spectra were examined in a region (750-950 cm-1) in which sulphate half-ester absorptions occur. Changes seen in this region when metal ion-heparin complexes are converted into heparinic acid, when heparin is carboxy-group-reduced and when various concentrations of Li(+)-heparin are examined are tentatively interpreted in terms of changes in the ring conformation of iduronate residues.

Chemical Phenomena↗